1. Field of Invention
This invention relates to hand tools and is particularly directed to improved hand tools for cutting flex-duct material and the like.
2. Prior Art
In the heating and air conditioning industry, it is conventional practice to install a central furnace or air conditioning unit at a desired location within a house or building and to connect the central unit to outlet vents located at various remote locations about the building by means of suitable ducting. In the past, such ducting was usually formed of thin-walled aluminum or steel cylinders, which were wrapped in layers of insulating material. However, such rigid ducting was difficult and time-consuming to work with and, hence, was quite expensive. More recently, such rigid ducting has been replaced by flex-ducting, having a tube of flexible material, such as plastic or fabric, supported by a helical wire and having a layer of insulating material secured about the flexible tube. As the name suggests, the flex-duct material is quite flexible and, hence, is easy to curve about chimneys and other obstacles. However, cutting the flex-duct material to desired lengths presents some problems. The flexible tube can be cut quite easily with a cutter, such as a knife, razor blade or the like. However, the helical wire supporting the tube is quite strong and can only be severed by wire cutters or the like. Moreover, in cutting the tube with a knife or razor blade, the cutter frequently strike the wire supporting the tube, which tends to nick or dull the cutter blade. This greatly reduces the useful life of the cutter and necessitates that the user make frequent changes from the knife or razor blade to wire cutters, in order to cut the supporting wire, which involves considerable loss of time and significantly increases the labor cost of installing the flex-duct material. Numerous devices have been proposed heretofore for overcoming this problem. Thus, one recent device has been proposed comprising a plier-type tool having a knife blade fixed to one handle and wire cutter blade fixed to the other and cooperating with a second wire cutter blade formed at the base of the knife blade. This eliminates the necessity of changing from the tube cutting tool to the wire cutting tool and, hence, reduces the time required for performing a given cutting operation. However, the knife blade of this device is still subject to nicking, due to striking the supporting wire of the flex-duct, and, consequently, will rapidly become dull and will require frequent resharpening. Thus, none of the prior art devices have been entirely satisfactory.